1. Field of Invention
An improved cab suspension member to replace an existing factory suspension providing a terminal tractor with an improved rear suspension to improve the ride and performance of a terminal tractor, the improved rear suspension installed after market or provided as an original factory installation, the improved rear suspension members applied under the rear cab portion of the terminal tractor, increasing the suspension support and also redistributing the load upon the terminal tractor cab.
2. Description of Prior Art
A preliminary review of prior art patents was conducted by the applicant which reveal prior art patents in a similar field or having similar use. However, the prior art inventions do not disclose the same or similar elements as the present improved terminal tractor rear suspension system, nor do they present the material components in a manner contemplated or anticipated in the prior art.
A suspension system for a vehicle cab including springs and a sway resisting torsion bar is disclosed in U.S. Pat. No. 6,073,714 to McHorse, et al. which is provided to minimize lateral sway of the cab, primarily through use of a bushing or a singular spring and the torsion bar. A combination spring/shock absorber is disclosed in U.S. Pat. No. 5,590,733 to Ljungholm, et al. in which four shock absorbers with external springs are provided to cushion the cab of a tractor truck, also employing a second shock absorber on a lateral arm for diagonal reinforcement and suspension. A vibration dampening shock absorber is disclosed in U.S. Pat. No. 5,253,853 to Conaway, et al.
A two stage dampening shock absorber is disclosed in U.S. Pat. No. 5,249,652 to Leitzman, et al., which provides a primary force dampener with a second, stronger force dampener within the single shock absorber. U.S. Pat. No. 5,209,316 to Bauer and U.S. Pat. No. 4,871,189 to Van Breemen both disclose suspension systems using air springs, an air reservoir, shock absorbers and height control valves. A dual spring suspension system for railroad cars, having an inner coil spring with an additional stronger outer coil spring is disclosed in U.S. Pat. No. 4,186,914 to Radwill, et al.
In U.S. Pat. No. 6,408,970 to Eng (same inventor as in this present application) a three point cab suspension system for a terminal tractor provides for two front mount assemblies and one single rear mount assembly to redistribute the central mass of the terminal tractor and provide for a more stable and comfortable ride. Since the issuance of that patent, several subsequent patents address cab suspension systems. In U.S. Pat. No. 6,726,272 to Puterbaugh, an air spring damping system is disclosed to replace two to four points of the cab suspension system with the improved air spring suspension member. U.S. Pat. No. 6,986,545 to Nilsson discloses a cab suspension device having two stacked components, including a first element for the absorption of shock and vibration from the vehicle frame and a second element to act as a load support between the cab and the frame.